There is a need to code an image signal so as to effectively write still pictures or moving pictures in a storage medium or effectively transmit the still pictures or the moving pictures. Various methods have been proposed so as to improve efficiency at the time of coding. As a representative method, there are a method of using temporal prediction and a method of using spatial prediction.
The temporal prediction is to detect a prediction block having the smallest residual coefficients for object blocks of a current frame from other frames temporally approaching the current frame and is referred to as inter prediction.
The spatial prediction uses reconstructed pixel values of reference blocks adjacent to object blocks within a single frame to obtain prediction pixel values of the object blocks and is referred to as intra prediction.
Deblocking filtering may not be applied to spatially adjacent reconstructed signals that are used during a process of performing the intra prediction according to the related art, such that blocking artifacts occur. In addition, the adjacent reconstructed signals use only pixels in an integer pel unit. Further, the process of performing the intra prediction according to the related art is performed by using only the object signals of coding and the adjacent reconstructed signals, such that the spatially limited intra prediction is performed.